Optical absorption and EPR spectral studies of vauquelinite

Abstract

Vauquelinite -a mineral -was investigated by EPR, NIR and optical spectroscopic techniques. EPR studies on powder sample confirm the presence of Cu(II) and Fe(III) impurity in the mineral. Optical absorption spectrum also indicates that Cu(II) impurity is present in rhombically distorted octahedral structure and Fe(III) in octahedral structure. NIR results are due to water fundamentals and phosphate combination tone.

Study of Photocatalytic Activities with Copper Hydroxyphosphate

“…1 are obviously different. The relative intensities of (110), (220), (130), (330) and (440) planes in the sample prepared at low pH(3,4,5) as compared with those of other powders prepared at higher pH(6,7,8,9) were attributed to the anisotropic grain morphology, but the reflection peak of the those plane was not shifted to a lower diffraction angle or a higher diffraction angle when the pH was increased. From these XRD results, therefore, it is expected that the control of the pH involve the variations of morphology and crystalstructure.…”

“…Copper hydroxyphosphate (Cu 2 (OH)PO 4 ) has an orthorhombic crystal structure and consists of a PO 4 tetrahedron, a Cu(1)O 6 octahedron, a Cu(2)O 5 trigonal bipyramid, and an OH group between the two Cu species, in which oxygen atoms are shared with each other [4]. Cu 2 (OH)PO 4 has been found various physical and chemical properties, for example, the morphological [5], structural [6], optical [7], vibrational [8], and catalytic properties [9], of natural and synthetic libethenite have been investigated. Cu 2 (OH)PO 4 have excellent catalytic properties originate from the OH species attached to the Cu sites, which act as adsorption sites on the catalyst surface [10].…”