Solid State Synthesis, Solid State Synthesis, Phase Diagrams and Solid Phase Diagrams and Solid

SolutionsSolutions

Chemistry 123Spring 2008

Dr. Woodward

Solid State ReactionsSolid State Reactions

Micron Sized Powders(Starting Materials)

Example: MgO(s) + MoO3(s) MgMoO4

1 Grind 2

Heat

3

Repeat Grind &

Heat

4

Two Component Phase Two Component Phase DiagramDiagram

Mole % ZnS

0 25 50 75 100

Liquid

2-phase region

MgS (ss) + ZnS (ss)

MgS (ss) + Liquid ZnS (ss) +

LiquidMgS (ss)

ZnS (ss)

Tem

pera

ture

(C

)

Pure ZnSPure MgS

A

B

C

Eutectic Point

D

Mole %

0 25 50 75 100

Liquid

2-phase region

(ss) + (ss)

(ss) + Liquid (ss) +

Liquid(ss)

Tem

pera

ture

(C

)

Pure Pure

Eutectic Point

Rock salt type Mg1-xZnxS

Zinc Blende type Zn1-xMgxS

Microscopic View

Region A Region BRegion CMicroscopic View Microscopic View

Homogeneous Solid Solution

Mg0.8Zn0.2S

Homogeneous Solid Solution

Mg0.1Zn0.9S

Two phase (heterogeneous)

mixture

Mg0.8Zn0.2S + Mg0.1Zn0.9S

How can we analyze materials to determine their composition and heterogeneity.

X-ray FluorescenceX-ray FluorescenceIncoming X-ray photon

ejected e−

11 Emitted photon22 33

Principle Quantum #

Subshells Electron Shell Label

# of Electrons in

Shell

1 1s K 2

2 2s, 2p L 8

3 3s, 3p, 3d M 18

4 4s, 4p, 4d, 4f N 32Because the energy levels between different shells change from element to element (because the effective nuclear charge is changing) the energy of the secondary X-rays that are emitted are different for each element. By measuring the energies of the secondary X-rays we can determine which elements are present and their approximate ratios.

keV (Energy)

8.04

8.63 keV

9.58

Zn K

Zn K

Cu KU.S. Penny (2008)

Zinc nitrate

Zn K8.63 keV

keV (Energy)

Zn K

5 6 7 8 9 10 11 12

Kα Kβ

Lα LβEn

erg

y

K shelln = 1

L shelln = 2

M shelln = 3

N shelln = 4