© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim pss current topics in solid state physics c status solidi www.pss-c.com physica Phys. Status Solidi C 8, No. 9, 2735–2738 (2011) / DOI 10.1002/pssc.201084052 The influence of Cd 2+ and Mg 2+ on the electrical and thermal properties of manganese mercury thiocyanate crystals and its Lewis base adducts-future materials for photonics device fabrication Santhosh Kumar R. 1 , S. Chandralingam 2 , Sijosh George 3 , Sreekanth G. 3 , Michael Augustine 3 , and Ginson P. Joseph 3* 1 Department of Physics, St. George’s College Aruvithura, Kottayam-686622, Kerala, India 2 Department of Physics, Jawaharlal Nehru Technological University, Hyderabad-500085, India 3 Department of Physics, St. Thomas College Pala, Kottayam-686574, Kerala, India Received 3 October 2010, accepted 4 February 2011 Published online 24 May 2011 Keywords organobimetallic, dielectric, TGA-DTA * Corresponding author: e-mail ginsonpj@gmail.com, Phone: + 91-9447064652 © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Growth of organo-metallic single crystals has been a subject of perennial concern to realize the use of these ma- terials for device applications. An important aspect of util- izing organo-metallic structure for nonlinear optical appli- cations is their unique charge transfer transitions, either from metal to ligand or ligand to metal [1]. Thiocyanate (SCN - ) is a highly versatile ambidentate ligand with two terminal modes and thirteen multidentate bridging modes of coordination. The concept developed by Pearson [2] on the hard and soft acids and bases rationalizes that the soft cations show a pronounced affinity for coordination with softer ligands, whereas, the hard cations prefer coordina- tion with harder ligands. In these complexes, mercury is usually tetrahedrally S-coordinated, while the ion of the metal may be surrounded by four or six ligands. For in- stance, the –SCN- ligands in MnHg(SCN) 4 bridge the tet- rahedrally coordinated N-bonded Mn atoms and the tetra- hedrally coordinated S-bonded Hg atoms into a 3-D net- work with space group 14 [3]. . MnHg(SCN) 4 exhibits high hyperpolarizability due to the extended π-conjugation of the Mn-NCS-Hg bridges and their parallel alignments in the 3-D crystal structure. This 3-D network provides a lar- ger domain for polarizability, which in turn induces a large macroscopic nonlinearity. As second order nonlinear opti- cal (SONLO) materials, bimetallic thiocyanates such as ZnCd(SCN) 4 , ZnHg(SCN) 4 , CdHg(SCN) 4, CoHg(SCN) 4, MnHg(SCN) 4 (C 2 H 6 O 8 ) 2 CdHg(SCN) 4 (C 2 H 6 O 8 ) 2 and MnHg(SCN) 4 (abbreviated as ZCTC, ZMTC, CMTC, MMTD,CMTD and MMTC, respectively), exhibit rela- tively high SHG efficiecy than urea, KDP, at short wave- lengths [4]. The metal thiocyanates and their Lewis-base adducts are one of the interesting themes of structural chemistry [5]. This encouraging switch over is mainly attributed to the improvement of NLO property by the addition of DMSO ligand. The introduction of DMSO aids better electronic oscillations in SCN ligand, leading to an enhancement in NLO efficiency. The present study explains the influence of metal on manganese mercury thiocyanate (MMTC) and manganese mercury thiocyanate bisdimethylsulfoxide (MMTD), a Lewis base adducts of MMTC. The second Single crystasls of pure and doped MMTC and MMTD crys- tals were grown by slow evaporation technique. The TGA traces of doped crystals show a marginal increase in the ther- mal stability of the samples. The influence of metal substitu- tion on the dielectric properties of the MMTC and MMTD crystals has been investigated and reported.