Photoluminescence properties of Ca4La6(SiO4)4(PO4)2O2-based phosphors for wLEDs

Ju Cheng; Jia Zhang; Jian Lu; Xintian Bian; Hongchao Zhang; Zhonghua Shen; Xiaowu Ni; Pengcheng Ma; Jin Shi

doi:10.3788/COL201917.051602

Abstract

The apatite compound Ca₄La₆(SiO₄)₄(PO₄)₂O₂ (CLSPO) was explored as the host material for phosphors used in white light-emitting diodes (wLEDs). The crystal structure of the CLSPO host prepared by the solid-state reaction method was investigated with Rietveld refinement. The rare earth ions (Eu³⁺/ Tb³⁺/Ce³⁺, Tb³⁺/Tb³⁺, Mn²⁺) activated CLSPO phosphors were synthesized, and their photoluminescence properties, quantum yields, as well as thermal stabilities, were studied. Under near-ultraviolet excitations, the Eu³⁺ and Tb³⁺-doped CLSPO compounds exhibited red and green emissions with high luminescence efficiencies. Besides, tunable emissions from green to orange were obtained by introducing Mn²⁺ ions into the Tb³⁺-doped CLSPO samples. The results showed that the phosphors studied may have potential applications for wLEDs.

Table S1. Final refined structure parameters of CLSPO host

Atom	Wyckoff position	Atomic coordinates			Occupancy
Atom	Wyckoff position	x	y	z	Occupancy
Ca1	4f	0.6666670(0)	0.3333330(0)	0.0011650(0)	0.754(3)
Ca2	6h	0.2293970(0)	0.9850930(0)	0.2500000(0)	0.272(0)
La1	4f	0.6666670(0)	0.3333330(0)	0.0011650(0)	0.246(3)
La2	6h	0.2293970(0)	0.9850930(0)	0.2500000(0)	0.738(0)
Si	6h	0.4081860(0)	0.3824410(0)	0.2500000(0)	0.582(0)
P	6h	0.4081860(0)	0.3824410(0)	0.2500000(0)	0.418(0)
O1	6h	0.6693150(0)	0.5113230(0)	0.2500000(0)	1.000(0)
O2	6h	0.3111750(0)	0.4678460(0)	0.2500000(0)	1.000(0)
O3	12i	0.3340830(0)	0.2661990(0)	0.0576390(0)	1.000(0)
O4	2a	0.0000000(0)	0.0000000(0)	0.2500000(0)	1.000(0)
Space group: P63/m (176); cell parameters: a=b=9.595 Å, c=7.088 Å, V=565.121 Å3. Reliability factors: χ2=3.146, Rwp=7.58%, Rp=6.23%.

Table S2.Cell parameters of the samples

Sample	a (Å)	b (Å)	c (Å)	V (Å3)
CLSPO	9.595	9.595	7.088	565.121
CLSPO: 0.90Eu3+	9.559	9.559	7.042	557.283
CLSPO: 0.90Tb3+	9.556	9.556	7.037	556.502
CLSPO: 0.90Tb3+, 0.52Mn2+	9.560	9.560	7.030	556.433
CLSPO: 0.06Ce3+, 1.20Tb3+	9.557	9.557	7.016	555.036