Sr

2

CeO

4

with one-dimension structure is a new kind of material. The special structure leads to its photoluminescence properties. From JCPDS

Sr

2

CeO

4

was in the triclinic crystal system with cell parameters a=6.070Å

6=8.976Å

c=10.598Å

a=94.7°

β=90.4°

γ=95.8°. But it was reported recently that Sr

2

CeO

4

was orthorhombic cell with a=6.11897Å

b=10.3495Å

c=3.5970Å. This was maybe caused that some key weak reflections were omitted. Sr

2

CeO

4

structure consists of linear chains of edge-sharing CeO

6

octahedra that run parallel to the [001] crystallo-graphic direction with a repeat distance of 3.597Å. There are two kinds of Ce-O bonds in the structure Ce-O and Ce-O-Ce

and the bond length of the former is 0.1A shorter then that of the latter. When Sr

2

CeO

4

is excited at 310nm

the process of energy transfer may carry throng successfully because Ce-O bond is shorter than Ce-O-Ce bond

so strong fluorescence caused by charge transfer can be observed.

M

2

CeO

4

(

M

=Ca

Sr

Ba) were prepared

and it was found that Ba

2

CeO

4

which has a similar structure with Sr

2

CeO

4

can emit fluorescence

but Ca

2

CeO

4

which has a different structure can't emit fluorescence. The fluorescence of Ba

2

CeO

4

is weak

which is caused by the larger Ba

2+

radium leading to lattice expanding and making energy transfer difficult. Ca

2

CeO

4

has a different structure

that is to say

there is no one-dimension chain in the structure of Ca

2

CeO

4

and no energy transfer

so that the fluorescence of Ca

2

CeO

4

can't be observed. The characteristics of one-dimension structure compounds can be summarized:(1) A shorter M-O bond in the one-dimension structure may lead to fluorescence caused by charge transfer.(2) M has alterable valence

and in the one-dimension structure M has a higher valence and the lower valence M can emit fluorescence.(3) The emitting band and exciting band are always broad

which is in favor of making use of energy.(4) The fluorescence caused by charge transfer is easy in one-dimension structure

which leads to the fluorescence of some compounds that can't emit fluorescence in other structures.