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Balasubramanian V, Kannan S, Thangaraj NS, Sivakumar G, Mohanraj K. Role of W‐Rich CuWO
4
and Doped Zn‐CuWO
4
Ceramics and Its Improved Photoelectrochemical Cell Performances Synthesized by Solid State Reaction Method. ChemistrySelect 2020. [DOI: 10.1002/slct.202000229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Selvaraj Kannan
- Department of PhysicsExcel Engineering College Namakkal 637 303, Tamil Nadu India
| | - Nishanthi S. Thangaraj
- Central Electrochemical Power sources divisionCentral Electrochemical Research Institute (CECRI) Karaikudi 630 003, Tamil Nadu India
| | - Ganesan Sivakumar
- CISL, Department of PhysicsAnnamalai University Annamalai nagar 608 002, Chidambaram Tamil Nadu India
| | - Kannusamy Mohanraj
- Department of PhysicsManonmaniam Sundaranar University Tirunelveli 627 012, Tamil Nadu India
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Souza ELS, Sczancoski JC, Nogueira IC, Almeida MAP, Orlandi MO, Li MS, Luz RAS, Filho MGR, Longo E, Cavalcante LS. Structural evolution, growth mechanism and photoluminescence properties of CuWO 4 nanocrystals. ULTRASONICS SONOCHEMISTRY 2017; 38:256-270. [PMID: 28633825 DOI: 10.1016/j.ultsonch.2017.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/06/2017] [Accepted: 03/06/2017] [Indexed: 05/27/2023]
Abstract
Copper tungstate (CuWO4) crystals were synthesized by the sonochemistry (SC) method, and then, heat treated in a conventional furnace at different temperatures for 1h. The structural evolution, growth mechanism and photoluminescence (PL) properties of these crystals were thoroughly investigated. X-ray diffraction patterns, micro-Raman spectra and Fourier transformed infrared spectra indicated that crystals heat treated and 100°C and 200°C have water molecules in their lattice (copper tungstate dihydrate (CuWO4·2H2O) with monoclinic structure), when the crystals are calcinated at 300°C have the presence of two phase (CuWO4·2H2O and CuWO4), while the others heat treated at 400°C and 500°C have a single CuWO4 triclinic structure. Field emission scanning electron microscopy revealed a change in the morphological features of these crystals with the increase of the heat treatment temperature. Transmission electron microscopy (TEM), high resolution-TEM images and selected area electron diffraction were employed to examine the shape, size and structure of these crystals. Ultraviolet-Visible spectra evidenced a decrease of band gap values with the increase of the temperature, which were correlated with the reduction of intermediary energy levels within the band gap. The intense photoluminescence (PL) emission was detected for the sample heat treat at 300°C for 1h, which have a mixture of CuWO4·2H2O and CuWO4 phases. Therefore, there is a synergic effect between the intermediary energy levels arising from these two phases during the electronic transitions responsible for PL emissions.
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Affiliation(s)
- E L S Souza
- PPGQ-CCN-GERATEC, Universidade Estadual do Piauí, Rua: João Cabral, N. 2231, P.O. Box 381, 64002-150 Teresina, PI, Brazil
| | - J C Sczancoski
- DQ-UFSCar, Universidade Federal de São Carlos, P.O. Box 676, São Carlos, SP 13565-905, Brazil
| | - I C Nogueira
- ICE-Universidade Federal do Amazonas, Av. Rodrigo Otávio Japiim, P.O. Box 670, 69077-000 Manaus, AM, Brazil
| | - M A P Almeida
- CCT-Universidade Federal do Maranhão, P.O. Box 322, 65080-805 São Luís, MA, Brazil
| | - M O Orlandi
- Departamento de Físico-Química, Universidade Estadual Paulista, 14800-060 Araraquara, SP, Brazil
| | - M S Li
- IFSC-Universidade de São Paulo, P.O. Box 369, 13560-970 São Carlos, SP, Brazil
| | - R A S Luz
- PPGQ-CCN-GERATEC, Universidade Estadual do Piauí, Rua: João Cabral, N. 2231, P.O. Box 381, 64002-150 Teresina, PI, Brazil
| | - M G R Filho
- PPGQ-CCN-GERATEC, Universidade Estadual do Piauí, Rua: João Cabral, N. 2231, P.O. Box 381, 64002-150 Teresina, PI, Brazil
| | - E Longo
- Departamento de Físico-Química, Universidade Estadual Paulista, 14800-060 Araraquara, SP, Brazil
| | - L S Cavalcante
- PPGQ-CCN-GERATEC, Universidade Estadual do Piauí, Rua: João Cabral, N. 2231, P.O. Box 381, 64002-150 Teresina, PI, Brazil.
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Ruiz-Fuertes J, Segura A, Rodríguez F, Errandonea D, Sanz-Ortiz MN. Anomalous high-pressure Jahn-Teller behavior in CuWO4. PHYSICAL REVIEW LETTERS 2012; 108:166402. [PMID: 22680738 DOI: 10.1103/physrevlett.108.166402] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Indexed: 05/17/2023]
Abstract
High-pressure optical-absorption measurements performed in CuWO(4) up to 20 GPa provide experimental evidence of the persistence of the Jahn-Teller (JT) distortion in the whole pressure range both in the low-pressure triclinic and in the high-pressure monoclinic phase. The electron-lattice couplings associated with the e(g)(E⊗e) and t(2g)(T⊗e) orbitals of Cu(2+) in CuWO(4) are obtained from correlations between the JT distortion of the CuO(6) octahedron and the associated structure of Cu(2+) d-electronic levels. This distortion and its associated JT energy (E(JT)) decrease upon compression in both phases. However, both the distortion and associated E(JT) increase sharply at the phase-transition pressure (P(PT)=9.9 GPa), and we estimate that the JT distortion persists for a wide pressure range not being suppressed up to 37 GPa. These results shed light on the transition mechanism of multiferroic CuWO(4), suggesting that the pressure-induced structural phase transition is a way to minimize the distortive effects associated with the toughness of the JT distortion.
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Affiliation(s)
- J Ruiz-Fuertes
- Departamento de Física Aplicada-ICMUV, Universitat de València, Edificio de Investigación, c/ Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
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