The overall goal of this project is to determine properties of the H-He-C-N-O system, as represented by small molecules composed of these elements, that are needed to constrain theoretical models of the interiors of the major planets. Much of our work now concerns the H2O-NH3 system. This project is the first major effort to measure phase equilibria in binary fluid-solid systems in diamond anvil cells. Vibrational spectroscopy, direct visual observations, and X-ray crystallography of materials confined in externally heated cells are our primary experimental probes. We also are collaborating with the shockwave physics group at Lawrence Livermore Laboratory in studies of the equation of state of a synthetic Uranus fluid and molecular composition of this and other H-C-N-O materials under planetary conditions

Boone, S.

Cynn, H. C.

Nicol, M. F.

English

NASA Technical Reports Server

Sta tus  Report: NASA Grant NAGW-104 November 1, 1986 
- HIGH PRESSURE COSMOCHEMISTRY APPLIED 
MAJOR PLANETARY INTERIORS: EXPERIMENTAL STUDIES 
Inve s t i ga t or s 
Malcolm F. Nicol, Professor  of Chemistry 
Steven Boone, Postgraduate Research A s s i s t a n t  
Huyn-chae Cynn, Postgraduate Research Ass i s t an t  
Department of Chemistry and Biochemistry 
Universi ty  of C a l i f o r n i a  
Los Angeles, CA 90024 
SUMMARY 
The o v e r a l l  goa l  of t h i s  pro jec t  i s  t o  determine p r o p e r t i e s  of t h e  
H-He-C-N-0 system, as represented  by small  molecules composed of t h e s e  
elements,  t h a t  a r e  needed t o  cons t ra in  t h e o r e t i c a l  models of t h e  i n t e r i o r s  
of t h e  major p lane ts .  Much of our work now concerns t h e  H2O-NH3 system. This 
p r o j e c t  t h e  f i r s t  m a j o r  e f f o r t  t o  measu re  p h a s e  e q u i l i b r i a  i n  b i n a r y  
f l u i d - s o l i d  sys t ems  i n  diamond a n v i l  c e l l s .  V ib ra t iona l  spectroscopy,  d i r e c t  
v i s u a l  observa t ions ,  and x-ray c rys ta l lography of m a t e r i a l s  confined i n  
e x t e r n a l l y  heated c e l l s  a r e  our primary experimental  probes,  We a l s o  are  
c o l l a b o r a t i n g  w i t h  t h e  shockwave p h y s i c s  g roup  a t  Lawrence Livermore  
Laboratory i n  s t u d i e s  of t h e  equat ion of s t a t e  of a "synthe t ic  Uranus" f l u i d  
and  m o l e c u l a r  c o m p o s i t i o n  of  t h i s  and  o t h e r  H-C-N-0 m a t e r i a l s  unde r  
p l ane ta ry  condi t ions .  
6AS A-CE-177 188 ) HIG B PRESSUEE N87-11670 
C G S B O C H E H I S T R P  A P E L I E D  TO MAJCG P L A N E T A B Y  
IHTERIORS: E X F E b I E E N T A L  STUCIES S t a t u s  
REport { C a l i f c r r i a  Univ.) 4 F CSCL 0 3 3  Uriclas 
G3/91 43863 
https://ntrs.nasa.gov/search.jsp?R=19870002237 2020-03-20T14:01:21+00:00Z
T 
1 S t a t u s  Report: NASA Grant NAGW-104 
i 
November 1 ,  1986 Page 2 1 
Deta i l ed  Descr ip t ion  of Work in Progress  During t h e  Per iod  5/1/86-10/31/86 
During  t h e  s ix-months  c o v e r e d  by t h i s  r e p o r t ,  o u r  p r imary  f o c u s  
continued t o  be t h e  NH3-H2O system i n  t h e  composition range (NH3)x(H20)1-x, 
0 x ( 0 . 3 3 .  Dr.  Mary Johnson, a pos tdoc tora l  fe l low formerly on t h i s  
p r o j e c t  and now a t  t h e  Ca l i fo rn ia  I n s t i t u t e  of Technology, completed a 
manuscript  t h a t  desc r ibes  h e r  v i s u a l  observa t ions  of t h i s  system t o  5 GPa 
f rom 240 t o  370 K .  T h i s  s t u d y  p r o v i d e d  a g r e a t  amount o f  d e t a i l e d  
informat ion  about t h i s  sys t em at high pressures .  However, she  added t w o  
cavea ts :  (1) Ice V I  and ammonia d ihydra te  are d i f f i c u l t  t o  nuc lea t e  from t h e  
l i q u i d  so it i s  not  c l e a r  t h a t  equi l ibr ium boundaries among t h e s e  phases 
and  t h e  l i q u i d  have  been e s t a b l i s h e d .  ( 2 )  S o l i d  p h a s e s  c a n  n o t  be  
unambiguous ly  i d e n t i f i e d  by v i s u a l  o b s e r v a t i o n s .  T h i s  m a n u s c r i p t  was 
submit ted t o  t h e  e d i t o r s  of t h e  Journa l  of Geophvsical Research i n  August; 
a p r e p r i n t  i s  appended t o  t h i s  repor t .  
Our e f f o r t s  d u r i n g  t h e  Summer, t h e r e f o r e ,  emphas ized  two r e l a t e d  
a c t i v i t i e s :  (1) t r y i n g  t o  e s t a b l i s h  equi l ibr ium among Ice V I ,  ammonium 
d i h y d r a t e ,  and l i q u i d  by a p p r o a c h i n g  p h a s e  b o u n d a r i e s  f rom s e v e r a l  
d i r e c t i o n s  and ( 2 )  prepar ing  samples of pure phases i d e n t i f i e d  by D r .  
Johnson and ob ta in ing  t h e i r  x-ray d i f f r a c t i o n  p a t t e r n s  and v i b r a t i o n a l  
s p e c t r a  i n  o rde r  t o  augment v i s u a l  methods of i d e n t i f i c a t i o n .  Mr. Steven 
Boone continued t h e  work on t h e  phase boundaries by extending t h e  v i s u a l  
s t u d i e s  sys tem i n  t h e  diamond-anvil high pressure  c e l l s ,  e s p e c i a l l y  near  
33% "3. Several  samples were prepared and cycled repea ted ly  over a wide 
range of pres su res  and temperatures.  
Although Mr. Boone's work i s  not complete, some samples were not 
reproducib le  a f t e r  many cycles .  Three l i k e l y  sources  of i r r e p r o d u c i b l i t y  
a r e  being examined: (a) r e a c t i o n  among ammonia, water, gaske ts ,  and o t h e r  
components of t h e  high pressure  c e l l ,  ( b )  loss of m a t e r i a l  through cracks  i n  
t h e  gaske t ,  and ( c )  genera t ion  of new nuc lea t ion  si tes by cold working of 
t h e  gaske t  which might change t h e  r a t e s  a t  which equi l ibr ium phases appear.  
Mr. Boone is  a t tempt ing  t o  determine the  source of t h e  i r r e p r o d u c i b i l i t y  by 
observ ing  t h e  e f f e c t s  of d i f f e r e n t  gasket  m a t e r i a l s  on t h e  behavior of 
ammonia-water samples. With Mr. Cynn, he a l s o  i s  ob ta in ing  v i b r a t i o n a l  
s p e c t r a  of o s t e n s i b l y  pure phases so t h a t  t h e  mixed-phase reg ions  of t h e  
diagram can be cha rac t e r i zed  by spectroscopy. 
Mr. Boone also i s  superv is ing  cons t ruc t ion  of an  au toc lave  f o r  loading 
diamond a n v i l  c e l l s  w i t h  mixtures  of gases  a t  moderate pressures .  This  
appa ra tus  w i l l  be used t o  prepare methane-water and ammonia-methane samples. 
The au toc lave  is  being cons t ruc ted  from forged s teels  t h a t  are r e s i s t a n t  t o  
hydrogen embri t t lement .  Work on t h e  au toc lave  was temporar i ly  h a l t e d  when 
i n t e r n a l  c racks  were discovered i n  t h e  forg ing  which i s  being rep laced  by 
t h e  vendor. 
S t a t u s  Report: NASA Grant NAGW-104 November 1, 1985 Page 3 
Mr. Hyun-chee  Cynn,  a s e c o n d - y e a r  s t u d e n t  f r o m  t h e  G r a d u a t e  
Geochemistry Program of t h e  Department of Ear th  and Space Sciences,  began t o  
work on t h i s  p r o j e c t  d u r i n g  t h e  Summer. For h i s  f i r s t  t a s k ,  Mr. Cynn 
prepared c r y s t a l s  of ammonia d ihydra te  i n  a Merrill-Bassett diamond-anvil 
c e l l  w i th  beryl l ium rockers  t h a t  i s  e s p e c i a l l y  s u i t e d  f o r  s i n g l e - c r y s t a l  
x-ray d i f f r a c t i o n  work. The ob jec t ives  of t h i s  t a s k  are  t o  grow s i n g l e  
c r y s t a l s  of ammonia d ihydra te  a t  room and low temperatures and t o  determine 
whether t h e i r  s t r u c t u r e s  a r e  t h e  same a p a r t  from small e f f e c t s  of thermal  
expansion and compress ib i l i ty .  
The f i r s t  c r y s t a l s  were grown near room temperature  from approximately 
3l-mole-percent aqueous "3 i n  0.4-mm diameter  h o l e s  i n  0.2- t o  0.4-mm 
t h i c k  Inconel.  X gaske t s  between diamonds wi th  0.8-mm c u l e t s .  The ammonia 
d ihydra t e  was i d e n t i f i e d  by i t s  known o p t i c a l  an iso t ropy  under crossed 
p o l a r i z e r s .  The p res su re  was determined t o  be about 10 kbar  by t h e  ruby 
luminescence method. For the  i n i t i a l  x-ray study, t h e  c r y s t a l  was maintained 
a t  a p re s su re  s l i g h t l y  higher  than t h e  mel t ing  pressure .  
During September schedule,  Mr. Cynn obta ined  use of t h e  departmental  
Huber f o u r - c i r c l e  d i f f r ac tomete r  f o r  pa r t  of one week. This  was t h e  f i r s t  
time t h a t  he had used t h i s  d i f f r ac tomete r ,  and he managed t o  cen te r  t h e  
c r y s t a l  and t o  scan t h e  d i f f r a c t i o n  p a t t e r n  f o r  3 8  hours. He i d e n t i f i e d  
s e v e n  s t r o n g  i n d e p e n d e n t  r e f l e c t i o n s  f rom 1811 t h a t  were s o u g h t .  
P r e l i m i n a r y  a n a l y s i s  o f  t h e  d a t a  s u g g e s t  t h a t  ammonia d i h y d r a t e  h a s  a 
monoclinic-B s t r u c t u r e .  The observed l a t t i c e  cons t an t s  were: a = 709.80 pm, 
b = 568.86 pm, c = 886.64 pm, a = 90.0080, B = 109.5450, a n d y  = 90.4010. If 
t h e  c e l l  i s  monoclinic and conta ins  four  formulas, t h i s  would correspond t o  
a not unreasonable d e n s i t y  of 1.12 g ~ m - ~ .  
T h i s  f i r s t  s c a n  was t e r m i n a t e d  b e c a u s e  t h e  i n t e n s i t i e s  of many 
expected r e f l e c t i o n s  appeared t o  be very low. Observation of t h e  sample a t  
t h e  end of t he  scan suggested,  however, t h a t  t h e  weak s i g n a l s  r e s u l t e d  from 
p a r t i a l  mel t ing  of t h e  sample because of overn ight  temperature  f l u c t u a t i o n s  
i n  t h e  x-ray labora tory  and the proximity of t h e  pressure  and temperature  of 
t h e  sample t o  t h e  mel t ing  l i ne .  Since then, Mr. Cynn has  learned  t o  grow 
s i n g l e  c r y s t a l s  of d ihydra t e  a t  somewhat higher  pressures  and temperatures  
so t h a t ,  a f t e r  cool ing  t o  room temperature,  they a r e  f u r t h e r  away from t h e  
m e l t i n g  l i n e  and  l e s s  s u s c e p t i b l e  t o  t e m p e r a t u r e  f l u c t u a t i o n s .  The 
d i f f r a c t i o n  p a t t e r n s  of such c r y s t a l s  a t  room and low temperatures  w i l l  be 
obta ined  as soon as the  d i f f rac tometer  schedule  permits.  The techniques f o r  
growing s i n g l e  c r y s t a l s  of d ihydra t e  a l s o  a r e  being used by M r .  Cynn and 
M r .  Boone t o  prepare  c r y s t a l s  f o r  Raman and i n f r a r e d  spectroscopy. 
D u r i n g  t h e  p e r i o d ,  two p a p e r s  t h a t  d e s c r i b e d  D r .  J o h n s o n ' s  
phase e q u i l i b r i a  i n  c o n t r i b u t i o n s  t o  s t u d i e s  of high pressure  r e a c t i o n s  and 
t h e  Fe and C-H sys t ems  appeared i n  p r in t .  
S t a t u s  Report: NASA Grant NAGW-104 November 1, 1985 Page 4 
Bib l iographic  Data: 
Pub l i ca t ions  Appearing or Submitted Between 5/1/86 and 10/31/86 : 
R. Boehler,  M. Nicol, C.-S. Zha, and M.L. Johnson, "Resis tance 
Heat ing of Fe and W i n  Diamond-Anvil Cells", Physica B 139/140 
(1986) 916-918. 
M.L. Johnson,  M. N i c o l ,  and N.C. Holmes, "Molecular  E m i s s i o n  
Spec t ra  from Shock-Decomposed Benzene", i n  Y.M. Gupta, ed., Shock 
Waves in Condensed Matter (Plenum, New York, 19861, 201-206. 
M.L. Johnson and M. Nicol,  "The Ammonia - Water Phase Diagram 
and i t s  Impl ica t ions  f o r  Icy  S a t e l l i t e s , "  (Submitted t o  J. Geophys. 
Res.) 
Ta lks  Related t o  Work Done on t h i s  Contract  Presented Between 
5/1/86 and 10/31/86. 
I n v i t e d  Pos t e r :  N.C. Holmes, M.L. Johnson, and M. Nicol, "Emission 
Spectroscopy of Shocked Benzene", Gordon Research Conference on 
Research a t  High Pressures ,  Meridan, June 1986. 


High pressure cosmochemistry applied to major planetary interiors: Experimental studies

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