Tracing the Academic Legacy of Prof. Dipankar Das Sarma, Renowned Scientist from IISc Bengaluru: A Bio-Bibliometric Analysis of Scientific Productivity and Research Impact

INTRODUCTION

The rapid growth of scientific literature in recent decades has led to the increasing use of quantitative methods to assess research productivity, impact, and patterns of collaboration. In this context, bio-bibliometric analysis has emerged as a well-established approach for examining the development, structure, and influence of scholarly communication at the level of individual researchers across disciplines (Madhu and Kannappanavar, 2020). By employing indicators such as publication output, citation counts, authorship patterns, and keyword co-occurrence, such analyses provide valuable insights into the intellectual contributions and evolving research focus of individual scholars. In the domain of condensed matter physics and materials science, individual researchers have made significant contributions to both theoretical advancement and experimental development.

Among these, Prof. Dipankar Das Sarma (DDS), a distinguished scientist associated with the Indian Institute of Science (IISc) Bangalore, particularly in the Solid State and Structural Chemistry Unit (SSCU), has contributed extensively over several decades (IISc, n.d.). His research spans areas such as electronic structure, transition metal oxides, nanocrystals, and perovskite materials, reflecting a broad and interdisciplinary profile. Despite his substantial and widely cited body of work, systematic quantitative studies examining his publication trends, citation impact, and collaborative patterns remain limited. The present study, therefore, undertakes a Bio-Bibliometric analysis of his publications indexed in Scopus over an extended period. It focuses on key indicators, including annual publication trends, citation performance, authorship characteristics, collaboration patterns, and keyword-based thematic development, with the aim of providing a comprehensive assessment of his research contributions and their influence within the scientific community (Madhu et al., 2025; Pradeep et al., 2025).

REVIEW OF LITERATURE

A review of selected studies provides an overview of bio-bibliometric analyses focusing on research productivity, citation impact, and collaboration patterns of individual scientists. Relevant prior studies considered for the present investigation are outlined as follows:

Kalyane and Munnolli (1995), conducted a scientometric analysis of T. S. West, revealing a highly productive research career comprising 410 publications, with a productivity coefficient of 0.45 and a publication density of 8.54. The study indicates a strong collaborative orientation, with major contributions alongside R. M. Dagnall and G. F. Kirkbright, and the predominance of keywords were atomic fluorescence and atomic absorption spectroscopy reflects his sustained contributions to the field of analytical chemistry. Garg and Kumar (2019), examined the research productivity of Dr. Hari Chand Sharma, analysing his 595 publications, of which approximately 45% were journal articles published mainly in medium-impact journals from the UK, USA, and the Netherlands. The study highlights a strong collaborative pattern, reflected in a collaboration coefficient of 0.66 and co-authorship with over 1,000 researchers, with peak productivity observed during the age of 58-60 years. A high citation per paper further indicates that his work is well integrated into mainstream scientific research. Koley and Sen (2021), analysed the research output of A. P. J. Abdul Kalam, noting that his first publication appeared in 1974 at the age of 43 and that his most productive phase occurred during 2004-2008 (aged 73-77), with an average of five publications per year. His contributions were mainly as first and second author, with a higher share of books and festschrift publications, and the majority of his journal articles appearing in national journals. Gholampour and Noruzi (2022) studied significant contributions made by Wolfgang Glänzel who made a significant contribution on quantitative studies of science, earning the Derek John de Solla Price Award. Over a 37-year career, his 276 publications, predominantly collaborative reflect peak productivity during 2008-2017, with major research contributions in scientometrics, citation analysis, text mining, and bibliometric indicators, often in collaboration with scholars from KU Leuven and the Hungarian Academy of Sciences. Gupta et al. (2025) conducted a bibliometric study of Dr. Raju Vaishya (2008-2024), reporting a total of 318 publications that received 6,834 citations, with an average of 21.49 citations per paper, and identifying 2020-2024 as the most productive period (208 publications). The findings indicate a high level of collaboration (96.22%), including notable national (55.66%) and international (29.24%) contributions, highlighting the importance of collaborative research in enhancing scholarly impact in orthopedics.

OBJECTIVES OF THE STUDY

• To examine the growth and distribution of publications of Prof. Dipankar Das Sarma (DDS) over the study period.
• To analyse the temporal evolution of research productivity and impact across different phases of the author’s career.
• To analyse the citation impact and performance, including total citations, citation per paper, and highly cited works.
• To identify the authorship pattern and degree of collaboration, including single-authored, multi-authored, and mega-authored publications.
• To evaluate the collaborative research structure, including inter-institutional, national, and international collaborations.
• To assess the preferred sources of publication, including document types, journals, and impact factor distribution.
• To examine the thematic structure of research through keyword analysis and co-occurrence mapping.
• To identify the major research domains and influential works based on top-cited publications.

METHODOLOGY

The present study adopts a bio-bibliometric approach to examine the research productivity, citation impact, and collaborative patterns of Prof. Dipankar Das Sarma (DDS). Bibliographic data were retrieved from Scopus, a widely recognised source for peer-reviewed literature and a product of Elsevier. Publications were identified using author-based search strategies and refined to ensure accuracy and relevance, with data fields including publication year, document type, citations, authorship details, source titles, and keywords. The dataset was subsequently exported, organised, and cleansed using Microsoft Excel, which was also employed for descriptive and statistical analyses such as publication trends, citation indicators, authorship patterns, and collaboration measures. For network visualisation, VOSviewer was utilised to generate keyword co-occurrence maps and identify major research clusters. Standard scientometric indicators, including total publications, total citations, citation per paper, collaboration coefficient, and keyword co-occurrence measures, were applied to interpret the data, thereby enabling a systematic assessment of the author’s research performance, thematic orientation, and collaborative profile.

Data Analysis and Interpretation

Overall Publication Productivity of Prof. Dipankar Das Sarma (DDS)

As shown in Table 1, the publication pattern of Dipankar Das Sarma (DDS) reflects a sustained and influential scholarly career spanning 1980 to 2025 (Figure 1). Over this 46-year period, he produced 516 publications, which received 23,215 citations, yielding an overall Citation Per Paper (CPP) of 44.99. His research output shows a gradual but consistent rise, increasing from 3 publications in 1980 to 10 in 2025. The period 2004-2015 was the most productive, contributing 177 publications (34.30%) and 9,117 citations, whereas 1992-2003 recorded the highest citation intensity (CPP: 58.82), indicating the strong influence of publications produced during that phase. At the annual level, 2000 and 2004 stand out as the most impactful years, with CPP values of 146.56 and 145.11, respectively. The data also reveal a pronounced collaborative orientation, with 131 inter-institutional, 110 national, and 275 international collaborative publications, in addition to 140 funded papers, underscoring the broad collaborative base of his research activity.

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As presented in Supplementary Table S1, the publication pattern of Prof. DDS is overwhelmingly collaborative, with only 9 papers (1.74%) being single-authored. Three-authored papers formed the largest share, followed by four- and five-authored publications, while mega-authored papers also made a notable contribution. The consistently high collaboration coefficient (0.98-0.99) confirms that collaboration remained a defining characteristic throughout his career. Likewise, Supplementary Table S2 shows that two-authored publications accounted for the largest share (17.25%), followed by single-authored (16.47%) and three-authored papers (14.73%), indicating a balanced yet collaboration-oriented authorship structure. Further, Supplementary Table S3 highlights that the most productive cumulative phase was 2005-2009, contributing 81 publications (15.70%), followed by 2010-2014 and 2015-2019, each with 73 publications (14.15%). With 507 out of 516 papers being multi-authored, the overall collaboration rate of 0.98 clearly demonstrates that collaborative scholarship remained a stable and central feature of his research productivity across all career stages.

Publications Types

Table 2 presents the publications distribution by Prof. DDS. Out of a total of 516 publications, the highest 443 (85.85%) publications were in the form of research articles. Followed by, 33 (6.40%) publications were conference papers and 14 (2.71%) publications were review articles. In terms of citations counts, research articles received highest citations count with 21512 Total Citations (TC), followed by, review articles (TC-1081), and conference papers (TC-265). In terms 7 citations impact, review articles recorded the highest Citation Per Paper (CCP) of 77.21, followed by short survey received CCP of 67.00 and research article received CCP of 48.46.

International Collaborative Countries

Out of Prof. DDS total 516 publications, 272 (52.71%) publications were produced through international collaboration. These 272 publications accounted a total of 11234 citations (averaging 41.20 CCP). Through his 46-research career (1985-2025), Prof. DDS established scientific collaborations with 804 foreign authors affiliated with 448 organizations across 38 countries. Table 3 details with top nine collaborative countries in Prof. DDS research productivity. Prof. DDS Internationally Collaborative Papers (ICP’s) demonstrate his international collaboration networks as follows: The highest number of collaborations recorded with two European countries, particularly with Germany (92 publications, 33.82% share) and Italy (73 publications, 26.84% share); (ii) moderate number of contributions came from Japan (63 publications, 23.16% share), United States (62 publications, 22.79% share), Sweden (45 publications, 16.54% share); (iii) limited collaboration was found with countries such as France (29 publications, 10.66% share), UK (17 publications, 6.25% share), Austria (14 publications, 5.15% share), Switzerland (11 publications, 4.04% share). In terms of citation impact among the top nine collaborating countries, publication with co-authored works form Switzerland (CCP-52.09) and Sweden (CCP-42.76) achieved the highest citation impact. Figure 2 illustrates the Prof. DDS international collaborations network with top 9 foreign countries spread across four clusters, reflecting varying levels of scholarly engagement.

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Top Foreign Authors

In Prof. DDS 272 ICPs, a total of 804 foreign authors participated between the time-span of 1980-2025. Table 4 details about the contributions of top nine foreign eight or more publications contributions. Carlo Carbone from Forschungszentrum Jülich GmbH, Germany (TP-21, TC-507) and Atsushi Fujimore from The University of Tokyo, Japan (TP-21, TC-482) top foreign contributors with Prof. DDS. In terms citations impact, with Prof. DDS the impact was Wolfgang Gudat affiliated to Helmholtz-Zentrum Berlin für Materialien and Energie (HZB), Germany (TP-16, TC-1212, CCP-75.75) and Settimio Mobilio affiliated to Tohoku University, Sendai, Japan (TP-13, TC-968, CCP-74.46) were more impactful authors among foreign contributing authors.

Figure 3 illustrates the Prof. DDS co-authorship networks with top nine foreign authors collaborators, across four major thematic clusters of researchers. Cluster 1 (red) includes three authors: Carlo Carbone (TP-21; TLS-41); Roberto Cimino (TP-14; TLS-33); Wolfgang Gudat (TP-16-; TLS-36). Cluster 2 (green) three authors: Atsushi Fujimori (TP-21-; TLS-22); Olof Karis (TP-17; TLS-17). Cluster 3 (blue) includes two authors: Carlo Meneghini (TP-15; TLS-29); Settimio Mobilio (TP-13; TLS-27). Cluster 4 (yellow) includes two authors: Takafumi J. Sato (TP-8; TLS-16) and Takashi Takahashi (TP-8; TLS-16).

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Top Foreign Organisation

In total 448 foreign organisations collaborated with Prof. DDS out of 275 publications. Among them, the top eight organisations remarkable made twelve or more publications collaboration. Table 5 highlights the top eight leading foreign collaborative organization, the highest coloration came with Forshugszentrum Julich Gmbh, from Germany (TP-43, TP-1064) and Uppsala Universitet, Uppsala, Sweden (TP-38, TC-1515) In terms of citation impact, namely two affiliation recorded high in citations per papers (CCP): Max Planck Institute for Solid State Research, Baden-Wurttemberg, Germany (TP-12, TC-554, CCP-46.17) and The University of Tokyo, Tokyo, Japan (TP-28, TC-1375, CCP-49.11). Figure 4 shows the Prof. DDS parent affliation and his international collaboration network among top 8 foreign organisations.

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Top Indian Collaborators

Table 6 highlights the top 15 collaborators of Indian origin with Prof. DDS. Out of 220 Indian authors, 15 authors made remarkable contributions with five or more publications collaborations. In terms publications count, Priya Mahadevan recorded highest publications with 22 publications, followed by, Tanusri Saha-Dasgupta with 13 publications. In terms citations impact, six authors recorded highest Citations Per Publications (CCP) namely: Chintamani Nagesa Ramachandra Rao (CNR Rao) (TP-45, TC-1871, CCP-41.58) Priya Mahadevan (TP-34, TC-1369, CCP-40.26). In terms of citation impact: Sammer Sapra (TP-13, TC-1730, CCP-133.08) and Ranjani Viswanatha (TP-12, TC-1197, CCP-99.75) are top impact authors with Prof. DDS. Figure 5 illustrates the Prof. DDS co-authorship networks with top nine Indian authors collaborators.

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Top Indian Organisation

In total 80 Indian organisations collaborated with Prof. DDS out of 110 publications (Figure 6). Among them, the top ten organisations remarkable made 5 or more publications collaboration. Table 7 highlights the top leading Indian collaborative organization, in terms of publications count, two institutes contributed highest publications with Prof. DDS namely: Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru (TP-52, TC-1740) and Centre for Advanced Materials, Indian Association for the Cultivation of Science, Kolkata (TP-36, TC-1466). In terms citations impact, two organisation recorded highest Citations Per Publications (CCP) namely: Department of Materials Science, Indian Association for The Cultivation of Science, Kolkata (TP-8, TC-1254, CCP-156.75) and Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, Ka, India (TP-36, TC-2734, CCP-75.94). Figure 2 illustrates the collaborations network of Prof. DDS with top 10 Indian organisation spread across four clusters, reflecting varying levels of scholarly engagement.

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Citation Performance

Supplementary Table S4 details the citation of performance of Prof. DDS. In total of 516 publications, 29 (5.62% share) publications were uncited. Followed by, 375 (69.19%, TC-6254) publication between 1-50 citation range received moderately cited works and highly cited papers (≥ 51 citations) contribute disproportionately to impact, with 51-150 citations accounted 98 (18.99%, TC-9524) of the total citations. The elite group of high-impacted publications segments ranged from 201-650 together comprises of 24 (4.65%, TC-7437) publications of the overall citations.

Impact Factor Wise Distribution of Published Publication

Supplementary Table S5 presents the impact factor-wise distribution of publications of Prof. DDS. The highest number of publications, 180 (34.88%), appeared in low impact factor journals (0.0-0.99), followed by 146 publications (28.29%) published in non-impact factor (NA) journals. Publications in medium impact factor journals (1.0-3.99) accounted for 139 papers (26.94%), while only 12 publications (2.33%) were published in high impact factor journals (4.0-5.99). Finally, 39 publications (7.56%) were published in very high-impact journals (6.0-18.28). In terms of journal quartile: 247 (48%) publications published in Q3 listed journals, followed by, In Q2 listed journals published in 146 (28%) publications. In Q1 listed journals published in 103 (20%) publications and 20 (4%) publications journal quartile were not available (Figure 7).

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Top citations of Prof. DDS

Table 8 lists the highly cited publications of Prof. DDS and reflects the substantial academic influence of his research across several areas of physical science. The most cited paper, published in 1980 (XPES studies of oxides of second- and third-row transition metals including rare earths) in collaboration with Sarma, D.D., and Rao, C.N.R., received 641 citations, followed by another highly influential work published in 2000 (Electronic structure of Sr2FeMoO6), which accumulated 512 citations. A considerable number of these top-cited papers appeared in internationally reputed journals, particularly in the fields of condensed matter physics, materials science, and nanoscience. Thematically, these publications are largely associated with electronic structure analysis, transition metal oxides, perovskite materials, and semiconductor nanocrystals, indicating both disciplinary depth and interdisciplinary relevance. Overall, the citation pattern of these papers demonstrates the enduring scholarly significance and broad research visibility of his scientific contributions.

SIGNIFICANT KEYWORDS

Keywords play a crucial role in the accurate indexing of research publications. Across the 516 publications of Prof. DDS, a total of 2,314 keywords were identified, reflecting considerable thematic diversity in his research output. The most frequently occurring keywords were Perovskite (42), Electronic Structure (40), and Nanocrystals (40), while Nanocrystals recorded the highest Total Link Strength (TLS: 123), followed by Electronic Structure (87) and Perovskite (79). These patterns indicate that his research is primarily centred on condensed matter physics, materials science, and nanoscience, with strong emphasis on the structural and electronic properties of advanced materials (Table S6).

A co-occurrence analysis of 32 selected keywords resulted in the identification of three major clusters (Figure 8). These keyword clusters represent the principal research themes of Prof. DDS and highlight his major scholarly contributions to condensed matter physics and materials science.

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Cluster 1 (Red): Cadmium Compounds, Cadmium Sulfide, Chemical Structure, Energy Gap, Manganese, Nanocrystals, Nanoparticles, Nanostructured Material, Photoluminescence, Synthesis (chemical), X-ray diffraction, X-ray Photoelectron Spectroscopy, Zinc Oxide, Zine Sulfide. Cluster 2 (Green): Doping (additives), Electronic Structure, Ferromagnetic Materials, Ferromagnetism, Lanthanum Compounds, Magnetic Properties, Manganese Compounds, Metal Insulator Transition, Photoelectron Spectroscopy, Photoemission, Strontium Compounds, Transition Metals. Cluster 3 (Blue): Crystal Structure, Halide Perovskites, Magnetism, Perovskite, Single Crystals, Temperature.

CONCLUSION

The present bio-bibliometric analysis of Dipankar Das Sarma demonstrates a sustained and influential research career spanning 1980-2025, with 516 publications and 23,215 citations (CPP: 44.99). The findings indicate steady growth in productivity, with 2004-2015 emerging as the most productive phase, while earlier periods exhibited higher citation intensity, reflecting the foundational impact of his contributions. His publication profile is dominated by research articles, though review papers show comparatively higher citation impact, and the distribution across journal impact factors suggests a balanced publication strategy. A notable characteristic of his scholarly output is the strong collaborative orientation, evidenced by a high collaboration rate (0.98) and extensive national and international partnerships across 38 countries. The predominance of multi-authored works and wide institutional linkages highlights the importance of collaborative research in shaping his academic influence. Keyword and network analyses further reveal a coherent thematic focus on condensed matter physics, materials science, and nanoscience, particularly in areas such as electronic structure and perovskite materials. Overall, the study underscores that sustained productivity, collaborative engagement, and thematic consistency have been central to his enduring research impact.