# Presentation: 169166

## James W. Richardson, Jr. 
Deputy Director
Intense Pulsed Neutron Source Division
Argonne National Laboratory
www.pns.anl.gov

EPSCoR Workshop June 16, 2004

***Deputy Director***
***Intense Pulsed Neutron Source Division***
***Argonne National Laboratory***
***www.pns.anl.gov***
***EPSCoR Workshop June 16, 2004***

**The Intense Pulsed Neutron Source (IPNS)****at****Argonne National Laboratory**

## Intense Pulsed Neutron Source (IPNS)

***Intense Pulsed Neutron Source (IPNS)***

**DOE User Facility at Argonne National Laboratory**
**Co-located with:**
- Advanced Photon Source
- Center for Nanoscale Materials
- Strong scientific programs in Materials Sciences, Physics, Chemistry and Biology
**Operating since 1981**
**User Program**
- Proposals accepted twice/yr
- Fast access available: some instruments
- ~240 users/yr
- 150-200 publications/yr
**~26 weeks of operation / yr**
**Users from 14 EPSCoR states in past 5 years**
**Limited travel funds available for university users**

**Argonne National Laboratory**
**Argonne Illinois**

## IPNS:IPNS - the world’s first dedicated spallation source

**Neutrons are produced via spallation when high energy protons hit uranium target**
**Beam is pulsed at 30 Hz**
**Neutron energy resolved from time-of-flight**
**IPNS operates with cold (methane) moderators to produce spectra with high concentrations of long wavelength neutrons**

**95% reliability operation of accelerator**
**13 instruments situated on 12 beam lines**
**10 instruments in user program**
**Common user-base with APS and CNM**
**www.pns.anl.gov**

## IPNS:Instrument Suite (10 instruments in user program)

***IPNS:******Instrument Suite****** ******(******10 instruments in user program)***

**Large Scale Structures **
**Small Angle Scattering - ****SAND,**** ****SAD**
**Reflectometry - ****POSY I,**** ****POSY II**

**Diffraction**
**Powder diffraction - ****SEPD, GPPD, HIPD**
**Single crystal - ****SCD**
**Liquids and Amorphous Materials - ****GLAD**

**Inelastic Scattering **
**Direct geometry - ****HRMECS****, ****LRMECS**
**Inverse geometry - ****QENS,**** ****CHEX**

## IPNS:IPNS User Focus

**From day one, dedicated to teaching the importance and applications of neutron science through operation of a user program**
**IPNS instrument scientists are “free agents” where scientific focus is dictated by personal interest and correlation with IPNS capabilities**
**Life-blood of instrument operation is Scientific Assistant (SA) with bachelor/masters level degree (IPNS model is 1 scientist, 1 SA, 1 post doc per instrument)**
**Many examples of student and faculty short- to intermediate-term (3 month to 1+ year) appointments**
**Neutron / X-ray school held at ANL each summer through DEP-ANL**
**Offer opportunities for “scoping” experiments prior to submittal of formal proposals**
**7 scientists in IPNS, 3 in Material Sciences Division dedicated to neutron science, user support**
**Biophysics** - Pappannan Thiyagarajan - thiyaga@anl.gov
**Polymer science** - Jyotsana Lal - jlal@anl.gov
**Metal hydrides** - Alexander Kolesnikov - akolesnikov@anl.gov
**Proton dynamics** - Chun-Keung Loong  - ckloong@anl.gov
**Amorphous materials** - Chris Benmore - cbenmore@anl.gov
**Coordination chemistry** - Art Schultz - ajschultz@anl.gov
**Microporous, ceramic materials** - Jim Richardson - jwrichardson@anl.gov
**Magnetic thin films** - Suzanne te Velthuis - tevelthuis@anl.gov
**Solid state physics, magnetic materials** - Jim Jorgensen - jjorgensen@anl.gov
**Strongly correlated electron systems** - Ray Osborn - rosborn@anl.gov** **

## Properties of Neutrons and Neutron Scattering

**Neutral particles**
- Highly penetrating, non-destructive
- Severe environments
**“****See” nuclei**
- Sensitive to light atoms
- Can use isotope substitution
**Energies similar to energies of elemental excitations**
- Molecular vibrations, lattice modes
- Dynamics of atomic motion
**Wavelengths similar to atomic spacings**
- Structure sensitivity
- Structural information from 10-13 to 10-1 cm
**Magnetic moment**
- Magnetic structure
- Magnetic fluctuations
**Spin**
- Polarized beams
- Studies of nuclear orientation

**Important despite many orders of magnitude lower flux relative to X-rays**

## Recent Science at IPNS

**Nanomaterials**
- Nano-ceramics
- Polymers, co-polymers
- Nano-carbon
- Porosity in carbonaceous and ceramic nano-materials
**Soft matter**
- Polymers and biological materials
- Polymer electrolytes
- Protein self-assembly
**Hydrogen economy-related**
- Water-nanotube composites
- Solid oxide fuel cell materials
- Hydrogen storage materials
- Proton conductor membranes
- Mixed-conductor ceramic membranes
- Gas hydrates

**Electrochemistry**
- Li-ion conductors
- Polymer electrolytes
**Magnetic materials**
- Magnetic thin films
- Magnetic superlattices
- Electron correlations
**Exotic materials**
- Bulk metallic glasses
- Microporous catalysts, etc.
- Liquid HF
**Exotic environments**
- Levitated liquids
- High-pressure phases of ice
- Radiation-damage in nuclear materials
- High magnetic field (7T)

## Nano-materials:Suppression of Peptide Aggregation by Copolymer Formation

**Contrast matching used in SANS to isolate components**
- H2O and D2O have very different scattering strengths for neutrons
**Alzheimer’s Disease is third leading cause of death in U.S**.
- Characterized by aggregation of peptide fibers known as A
- Disruption of aggregation may be a way of treating the disease
- Formation of block copolymers with polyethylene glycol (PEG) appears to have desired effect; BUT WHY?** **
**Differing scattering power of constituents in mixtures (e.g., PEG and A******** peptide) can be used to determine state of aggregation**
**1:99 mixture of H****2****O and D****2****O shows strong contrast with both PEG and peptide**
- Data from single component sample show 45 Å radius peptide fibers
- Data from A -peptide composite show 65 Å radius characteristic of PEG encapsulation of peptide fibers

## Nano-materials:Suppression of Peptide Aggregation by Copolymer Formation

**Contrast matching used in SANS to isolate components**
- H2O and D2O have very different scattering strengths for neutrons
**Alzheimer’s Disease is third leading cause of death in U.S.**
- Characterized by aggregation of peptide fibers known as A
- Disruption of aggregation may be a way of treating the disease
- Formation of block copolymers with polyethylene glycol (PEG) appears to have desired effect; BUT WHY?** **
**Differing scattering power of constituents in mixtures (e.g., PEG and A******** peptide) can be used to determine state of aggregation**
**84:16 mixture of H****2****O and D****2****O shows strong contrast only with peptide**
- Data from single component and composite samples show  45 Å radius
- These data confirm that PEG resides at periphery of fiber, thus preventing fibril-fibril association
**SANS with SAXS**
- SANS - A aggregation in solution under realistic conditions
- Probe individual units in A and A-PEG copolymer
- Time-resolved SAXS -Early stages of aggregation in both A and A-PEG

## Nano-materials / Hydrogen:Carbon Nanotube-Confined Ice

**Vibration spectra from Inelastic Neutron Scattering indicate:**
- Weak hydrogen-bonded network in nanotube-ice
- Extended intermolecular water-water and O-O distances, short O-H covalent bonds
**Temperature dependence of mean-squared amplitude of hydrogen vibrations from Quasielastic Neutron Scattering indicate:**
- Smooth solid-to-liquid transition of water in nanotube-confinement
**Small Angle Neutron Scattering measurements demonstrate that:**
- Water is confined to interior of nanotubes (different mixtures of H2O and D2O)

***Nano-materials / Hydrogen:******Carbon Nanotube-Confined Ice***

## Nano-materials / Hydrogen:Carbon Nanotube-Confined Ice

**Vibration spectra from Inelastic Neutron Scattering indicate:**
- Weak hydrogen-bonded network in nanotube-ice
- Extended intermolecular water-water and O-O distances, short O-H covalent bonds
**Temperature dependence of mean-squared amplitude of hydrogen vibrations from Quasielastic Neutron Scattering indicate:**
- Smooth solid-to-liquid transition of water in nanotube-confinement
**SANS measurements demonstrate that:**
- Water is confined to interior of nanotubes (different mixtures of H2O and D2O)
**Theoretical contributions from University of Utah complete picture:**
- Some water molecules(red) form square-ice sheets wrapped into a cylinder
- Others (yellow)  form chains in the interior

***Nano-materials / Hydrogen:******Carbon Nanotube-Confined Ice***

## Nano-materials: Spin-Flop Transition in Antiferromagnetic Superlattice

***Nano-materials:****** ******Spin-Flop Transition in Antiferromagnetic Superlattice***

**“****Spin-flop” transition observed in bulk if sufficiently high field applied**
**Surface spin-flop transition predicted for finite superlattices confirmed with polarized neutron reflectometry**
- Initiation at surface
- Motion of domain wall into film and expansion
- Formation of anti-phase domains

## Combined Neutron and X-ray Studies of Glasses under Pressure

**S. Sampath (postdoc), J.L. Yarger (Wyoming), C.J. Benmore (IPNS),** **K. Leinenweber (Arizona)**

**Collaboration:**** **Synthesis, NMR and thermodynamic measurements performed at the University of Wyoming
- High pressure densification of glasses at Arizona State Univ.
- Neutron and x-ray experiments performed at IPNS and APS, Argonne, on both permanently densified glasses and *in-situ* at high pressure
- Observations of network collapse and determination of structural mechanism behind “polyamorphic” transitions

**Motivation: **Investigate “polyamorphic” transitions in glasses e.g. from a tetrahedral amorphous form in germania to an octahedral form at high pressure, analogous to polymorphic transitions in crystallography

- v-GeO2

***Combined Neutron and X-ray Studies of Glasses under Pressure***

## Mixed-conducting Ceramic Membranes

**Technologically important membranes have unique properties:**
- High oxygen/hydrogen conductivity along with electronic conductivity
- Long-term structural stability under steep pO2 gradients
- Typically perovskite-based oxides with oxygen vacancies
**Typical application is conversion of CH****4**** to syngas (CO + H****2****)**
- pO2 gradient generated
- Oxygen ions permeate membrane to react with CH4
- Membrane activated simply by passes gases across opposing surfaces
**Specialized furnace insert developed at IPNS for inducing pO****2**** gradient *****in situ***** for diffraction**

## In situ NPD Data for LSFC Ceramic Membrane

- _Static_
- Air

**Neutron diffraction measures:**
- Structure including lattice parameters and oxygen vacancy concentration
- Measured as function of time (30 min. increments) and pO2 (10-0.5 to 10-20)

## In situ NPD Data for LSFC Ceramic Membrane

- p(O2)=10-16 atm

- TOF NPD data

**Change in pO****2**** produces:**
- Shift in peak positions
- Increase in oxygen vacancy concentration

**In situ***** NPD Data for LSFC Ceramic Membrane***

## LSFC Structure Variation with pO2

**(La****0.2****Sr****0.8****)****3****Fe****1.5****Co****0.5****O****x****            (La****0.2****Sr****0.8****)****3****Fe****1.5****Co****0.5****O****x-******** + ********/2O****2**** **

**x = 6.7 **
**<Fe/Co>=3.6**

**x-******** = 6.3**
**<Fe/Co>=3**

**Fe****4+**** ******** Fe****3+**

**Notes:**
Each data points used in Rietveld refinements represent 2 hours’ runs
Several interesting results:
Behaviors of pO2 in reducing side
Compared with 236 phase behavior without pO2 gradients, 236 was persistently present 
in pO2” of 10-12 atm. 50 sccm air can only support the 236 in 10-12 atm but not in 10-15 atm.
150 sccm air can support 236 in 10-14 atm.

It seems that there are two competing rates: oxygen removal from lattice of 236 in reducing side, 
and oxygen refill from air side

## In situ NPD Data for LSFC Ceramic Membrane

- air

- p(O2)=10-16 atm

- TOF NPD data

**Peak positions and oxygen vacancy content consistent with values in static air**
- Suggests that majority of membrane has comparatively high effective pO2
- Smooth variation in effective pO2 across membrane would produce broad peaks
- Performance limited by reaction at reducing side of membrane

**In situ***** NPD Data for LSFC Ceramic Membrane***

## The Neutron Scattering Revolution

**Not much new development since the mid-1980’s**
**The Spallation Neutron Source being built at ORNL is a multi-lab construction project with $1.4B TPC**
- 5 year construction project complete in FY06
- Operation starting FY08 with 15-20 “best-in-class” instruments (many new concepts developed at ANL)
- Beam power >10 times the currently most powerful spallation source in the world (ISIS in UK)
**Enhancements at IPNS and other existing facilities**
- e.g., data-rate increases for most IPNS instruments in past 3 years (increases of 4-10 for ~half of them)
- Unique capabilities:  magnetism, polarized neutrons, ultra-cold neutron spectrum

**Collectively, developments will generate capacity of ≥3000 users/yr; up from ~1200 **
- Nearly double the number of world-class instruments available to US scientists
- Cooperation among facilities in neutron scattering education
- Growing opportunities for neutron science funding from DOE and NSF
**Collaborations develop on basis of one-on-one discussions**
- Come join the fun!