Phosphates as multifunctional materials were of vital importance in the environmental and energy fields. In the present work, a new cyclophosphate, potassium manganese phosphate (KMnP O ) (hereafter KMPO), was prepared by solid state method. Cations (Ag and Cu ) and anion (N ) were substituted into KMPO lattice via ion-exchange and solid state methods, respectively. The as-prepared materials were characterized by powder X-ray diffraction, SEM-EDS and UV-visible diffuse reflectance spectra. Rietveld refinement was carried out for parent material. All the prepared materials were found to crystallize in the hexagonal lattice and isomorphous with KCoP O . The nitrogen content in N -substituted KMPO was estimated by EDS and O-N-H analysis. The bandgap energy of the cation- and anion-substituted samples was lower compared to that of pristine KMPO. Gouy method was employed to determine the magnetic susceptibility of KMPO. The photoluminescence property of Mn in all the samples was studied, and the color coordinates were calculated using CIE 1931 chromaticity. The photocatalytic activity of visible light active material, N -substituted KMPO, was examined against the degradation of methylene blue and methyl violet at ambient conditions.

BACKGROUND: Phosphates of bivalent, trivalent, or quadrivalent transition metal cations with alkali or alkaline earth ions are promising materials in the field of materials science and technology. Anions-doped phosphate materials have attracted considerable attention due to their potential applications in environmental remediation by degrading organic pollutants to less harmful byproducts. Thus, in the present work nitrogen/sulphur was doped into KMn 4 (PO 4 ) 3 (KMnPO) to improve its visible light photocatalytic activity. RESULT: S or N-doped KMn 4 (PO 4 ) 3 (KMnPOS or KMnPON)were prepared by a solid state method. The photocatalytic activities of these materials were evaluated by photodegradation of methylene blue, methyl violet and 4-chlorophenol. Quenching studies were carried out to identify the reactive species during the photodegradation of dyes. The photoluminescence properties of phosphate materials were investigated, and the color coordinates were also calculated using CIE 1931 chromaticity. CONCLUSION: The color coordinates obtained give the information that KMnPO, KMnPON and KMnPOS phosphors were suitable for blue light LEDs. KMnPOS is a novel highly visible light responsive photocatalyst and can be reused at least four timesefficiently. The higher photocatalytic activity of KMnPOS can be attributed to its lower electron-hole recombination rate and generation of more • OH radicals during photoreaction. was prepared by the gel burning method. Stoichiometric amounts of AR grade KNO 3 , MnCO 3 and NH 4 H 2 PO 4 were dissolved in double distilled water separately and labeled as 'solution A', 'solution B' and 'solution C', respectively. The clear solutions A and B were slowly added to solution C in an ice bath. The chelating agent, citric acid, was added. The molar ratio of citric acid to metal ions was 2:1. The pH of the resultant metal citrate solution was adjusted to 6-7 using dilute ammonia solution.

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