Synthesis, structural, optical, thermal, magnetic and EPR investigations of the new phosphate KCuCr(PO4)2

• Published in: Journal of molecular structure Vol. 1258; p. 132640
• Main Authors: Akhrouf, Asmaa, Laajali, Youssef, Haddad, Mustapha, Hlil, El-kebir, Krimi, Saida
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.2022; Elsevier
• Subjects: CIE L a b; Condensed Matter; DTA/TGA; Green phosphate; Magnetic and optical properties; Materials Science; Physics; RGB; Rietveld refinement; SEM; Rietveld refinement; CIE L a b; DTA/TGA; SEM; Magnetic and optical properties; RGB; Green phosphate
• ISSN: 0022-2860; 1872-8014; 0022-2860
• DOI: 10.1016/j.molstruc.2022.132640

•Synthesis of the new phosphate KCuCr(PO4)2 through solid-state reaction route as a promising green ceramic pigment.•Crystal structure was determined using Fullprof program based on Rietveld method.•The main components of the crystal structure are the CrO6 octahedra, the Cu2O8 dimers, and two kinds of PO4 tetrahedra.•XRD, SEM, DTA/TGA, EPR, CIE L* a* b*, RGB, optical, and magnetic spectra were recorded. New phosphate KCuCr(PO4)2 has been elaborated by solid-state reaction route and characterized by various techniques. The structure was determined from X-ray powder diffraction using Fullprof software based on Rietveld refinement. KCuCr(PO4)2 crystallizes in the monoclinic system, P21/n (no.14) space group, and with the unit cell parameter : a = 7.861(2) Å, b = 9.828(2) Å, c = 9.002(2) Å, and β = 115.2° (1). Its structure consists of 3D - network built up from Cu2O8 units and CrO6 octahedra which construct rigid layers parallel to the bc plane. These layers connected by PO4 tetrahedra gave rise to large tunnels where K+ cations are located with nine-fold coordination. SEM analysis reveals an agglomeration state of the prepared material. DTA/TGA analysis shows good thermal stability of the crystalline powder indeed required for ceramic pigments. EPR spectrum presents a strong signal characterized a high dipole-dipole interaction (Cu2+- Cu2+, Cr3+- Cr3+ and Cu2+- Cr3+). The green color of the investigated material was mainly due to the presence of Cr3+ and Cu2+ ions in six and five-fold coordination, respectively. UV Visible spectrum consists of several bands between 400 and 850 nm, assigned to d–d transitions of Cu2+ and Cr3+ ions; besides, a strong band around 294 nm was attributed to the O–M (M = Cu, Cr) charge transfers. CIE L*a*b*and RGB parameters values were determined to examine the material's color properties as a green ceramic pigment. Magnetic measurements reveal an antiferromagnetic behavior with TN = 17 K and θCW = −128K. [Display omitted]